add codegen support to union casts

init of static vars still not working. I'll get back to it tomorrow or so


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62278 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 24 insertions, 1 deletions

diff --git a/lib/CodeGen/CGExprAgg.cpp b/lib/CodeGen/CGExprAgg.cpp
index 7571149b5a..5e36751fb7 100644
--- a/lib/CodeGen/CGExprAgg.cpp
+++ b/lib/CodeGen/CGExprAgg.cpp
@@ -74,6 +74,7 @@ public:
   // Operators.
   //  case Expr::UnaryOperatorClass:
   //  case Expr::CastExprClass: 
+  void VisitCStyleCastExpr(CStyleCastExpr *E);
   void VisitImplicitCastExpr(ImplicitCastExpr *E);
   void VisitCallExpr(const CallExpr *E);
   void VisitStmtExpr(const StmtExpr *E);
@@ -127,6 +128,18 @@ void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
 //                            Visitor Methods
 //===----------------------------------------------------------------------===//
 
+void AggExprEmitter::VisitCStyleCastExpr(CStyleCastExpr *E) {
+  // GCC union extension
+  if (E->getType()->isUnionType()) {
+    RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
+    LValue FieldLoc = CGF.EmitLValueForField(DestPtr, *SD->field_begin(), true, 0);
+    EmitInitializationToLValue(E->getSubExpr(), FieldLoc);
+    return;
+  }
+
+  Visit(E->getSubExpr());
+}
+
 void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
   assert(CGF.getContext().typesAreCompatible(
                           E->getSubExpr()->getType().getUnqualifiedType(),
@@ -467,7 +480,7 @@ void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
     // Unions only initialize one field.
     // (things can get weird with designators, but they aren't
     // supported yet.)
-    if (E->getType()->isUnionType())
+    if (isUnion)
       break;
   }
 }
diff --git a/test/CodeGen/cast-to-union.c b/test/CodeGen/cast-to-union.c
new file mode 100644
index 0000000000..3f339041eb
--- /dev/null
+++ b/test/CodeGen/cast-to-union.c
@@ -0,0 +1,10 @@
+// RUN: clang -emit-llvm < %s | grep "store i32 351, i32*"
+
+union u { int i; };
+
+void foo() {
+  union u ola = (union u) 351;
+}
+
+// FIXME: not working yet
+// union u w = (union u)2;